Raised panel flooring, also known as access flooring, is used in a variety of situations, including ones where it is desirable or convenient to run cabling in a space under such flooring and ready access to the cables is desirable. The flooring panels may be supported by a pedestal and stringer structure such as that shown in U.S. Pat. No. 4,685,258, entitled "Access flooring with Increased Load Capacity," dated Aug. 11, 1987, which is incorporated herein by this reference. Other types and configurations of support structures will be apparent to one skilled in the art.
It is desirable for some of such panels to be perforated to permit airflow between the subfloor and the room. However, many conventional perforation patterns, such as the pattern illustrated in U.S. Design Pat. No. Des. 350,613, can present a problem when the traffic across them includes wheeled carts. Such patterns cause caster wheels and other wheels to chatter or bump up and down. This chattering or bouncing may jostle the carts. Ordinarily, such jostling is not harmful; however, in some situations the items held in the carts are extremely sensitive, such as silicon wafers used in the production of semiconductors. Even very slight jostling can damage these sensitive materials.
In addition to chatter caused by perforations, any misalignments between adjacent panels also may jostle the cart. For instance, any difference in height between adjacent panels can create a lip or step which will cause a jolt as a wheel passes from panel to panel. Likewise, gaps between panels also may induce undesirable jostling of the cart. Moreover, any deflection in a panel under load may cause the floor surface to be uneven, thereby inducing unwanted vibration or movement in carts being moved over the floor.
Furthermore, panels often are provided in different sizes. For example, panels may be dimensioned in English or Metric units. Consequently, the hardware associated with different sized panels generally corresponds to the selected size. Thus, manufacturers must make and users must stock two different sets of components, such as pedestal heads and stringers, substantially increasing handling costs.
A conventional pedestal head typically has bosses positioned about its periphery to help position the panels during installation. These bosses may actually interfere with the panel during removal operations, causing a "trap door" effect, i.e., if a user inadvertently rotates the panel during removal, the resulting resistance of panel to head may damage or even fracture the pedestal head in the removal process.
There is a need for a panel perforation pattern that causes minimal caster, or other wheel, chatter, which permits good airflow, and which is attractive. There also is also a need for panels that may be precisely aligned and which form continuous smooth joints with adjacent panels. There also is a need for panels having a high load carrying capacity, particularly at panel interfaces.